   "deactivate a feature for a particular group.
   A group is just a string"
   [{storage :storage} feature-name group]
-  (with-storage
+  (update-in-storage
     (fn [feature]
       (update-in feature
                  :groups

  [storage feature-name]
  (parse-feature feature-name (read-from-storage storage feature-name)))

(defn with-storage
  "alter a feature using the supplied function f. handles reading, serializing,
  deserializing, you just write f to modify the feature as wanted"
  [storage feature-name f]

(defn activate
  "completely activate a feature for all users"
  [{storage :storage} feature-name]
  (update-in-storage
    #(assoc %
            :percentage
            100)))
